1. Field
Embodiments of the present disclosure relate to a semiconductor device and a method for fabricating the same.
2. Description of the Related Art
The decrease in feature size of the MOS transistor has led into decrease in the gate length and the length of the channel. It is desired to increase capacitance between gates and channels, and to enhance operating characteristics of the MOS transistor.
Silicon oxide film is widely used for a gate insulating film, but as the silicon oxide film thickness decreases, there may be a physical limit in view of electric property. Accordingly, a high-k dielectric film having high dielectric constant may replace the silicon oxide film. The high-k dielectric film may reduce leakage current between gate electrode and channel region, while maintaining a thin equivalent oxide film thickness.
Further, polysilicon used as a gate material has greater resistance than many metals. Accordingly, a metal gate electrode may replace the polysilicon gate electrode.